1. Field of the Invention
The subject invention relates to manual quarter-turn valves intended primarily for ultra high purity gas flow systems.
2. Description of the Related Art
Many industries, such as the semi-conductor industry, require certain manufacturing processes to be carried out in the presence of a specified gas. Additionally, several different types of gas may be required at different locations or at different times in such a manufacturing facility. As a result, such manufacturing facilities include complex arrays of pipes that extend from the respective sources of gas to locations where the gases are required.
Manually operated quarter-turn diaphragm valves are disposed along these complex arrays of pipes for selectively starting and stopping the flows of different gases. The typical prior art manual quarter-turn diaphragm valve includes a valve housing having a valve chamber therein. An inlet extends from a first external location into the valve chamber, and an outlet extends from the valve chamber to a second external location. Portions of the inlet extending into the valve housing are axially aligned with portions of outlet extending from the valve housing. Thus, pipes leading into and out of the typical prior art diaphragm valve also will be axially aligned with one another.
A resiliently deflectable diaphragm is mounted across the valve chamber. The diaphragm can be deflected between a closed condition, where the diaphragm seals the inlet, and an open condition, where the diaphragm is spaced from the inlet. The prior art valve further includes an elongate valve stem that is orthogonal to the axially aligned portions inlet and outlet. The valve stem includes an inner end, an outer end and an intermediate portion that is threadedly engaged in the valve housing. A 90.degree. rotation of the valve stem causes the inner end of the valve stem to deflect the diaphragm between the fully opened condition and the fully closed condition.
A manual quarter-turn diaphragm valve includes an elongate handle that extends orthogonally from the outer end of the valve stem. The handle is secured to the valve stem to be parallel with the inlet and outlet when the valve is fully open, and to be orthogonal to the inlet and outlet when the valve is fully closed. Many prior art valves include a pointed projection that extends oppositely from the handle. The pointed projection and the handle effectively function as a directional arrow that indicates the opened or closed condition of the valve. Thus, technicians know that a valve is opened when the handle and the pointer are aligned with the inlet and outlet. Conversely, technicians know that a valve is closed when the handle and the pointer are aligned orthogonally to the inlet and outlet. This relative position of the handle and the pointer can be visually observed quickly and from a distance.
Many prior art valves are provided with visually apparent indicia to indicate the type of gas flowing through the valve. The indicia may include colors, words or chemical symbols to identify the gas. The gas-identifying indicia on prior art valves is very useful. However, the requirement for such indicia can complicate the management of inventory. Engineers and technicians must ensure that they maintain and/or order valves with the proper indicia for use each time a gas flow system is reconfigured or each time a valve is removed for repair or replacement.
Valves frequently must be placed close to one another or close to some other structure in a manufacturing facility. The proximity between a valve and some other structure can impede the ability to rotate the valve handle. More particularly, the valve handle must be sufficiently large to be easily gripped. However, a handle dimensioned for convenient manual gripping may be too large to be rotated 90.degree. within the limited available space. This problem can be overcome by replacing the valve with a new valve that has a reversed handle. However, significant cost and time are required to replace the affected valve.
The above-described problems associated with efficient rotation of a valve handle have been recognized in the prior art. For example, U.S. Pat. No. 5,647,389 shows a ball valve with an indexable latching handle assembly which permits the arc of operation to be oriented as necessary to avoid surrounding obstacles and thereby to ease operation. The valve of U.S. Pat. No. 5,647,389 includes a complex plurality of plates mounted over the valve stem for achieving any of a plurality of different orientations for the 90.degree. movement of the handle that is required to open or close the ball valve. The repositioned handle will not provide a visual indication of the relative opened or closed condition of the valve.
U.S. Pat. No. 4,559,966 relates to a ball valve that has a handle with a plurality of notches. A detent passes through a selected notch in the handle to engage fixed stops on the valve housing. By moving the detent to a different notch on the valve handle, the range of rotational movement of the handle can be varied.
U.S. Pat. No. 4,747,427 shows a ball valve with a locking plate having stops separated by 90.degree.. The plate can be inverted to change the permissible ranges of movement of the valve.
The above-described prior art relates to ball valves. The valve stem of a ball valve does not move axially into or out of the valving housing, but merely rotates. Additionally, the valving member of the ball valve has two fully opened conditions separated from one another by 180.degree. and two fully closed conditions separated from one another by 180.degree.. Thus, repositioning the handle on a ball valve can be carried out fairly easily by merely changing the end of the opening through the ball that will function as the inlet and/or by changing the direction of rotation between the opened and closed conditions. A diaphragm valve presents additional complications because the valve stem has only one fully opened position and one fully closed position which are separated by 90.degree..
Conventional sinks and exterior faucets are valves with manually activated valve stems. It often is desirable to position the handle on such a valve stem to achieve a specified aesthetic appeal. For example, it may be desirable to have handles on a conventional sink faucet facing away from one another and away from a centrally disposed spigot. Alternatively, some outdoor faucets may have an ornamental handle that desirably is aligned axially with the faucet. Handles of this type often include a cap that simply is telescoped over the valve stem. The cap can be rotated independently of the valve stem into a selected aesthetically desired orientation. The prior art cap includes a set screw extending radially therethrough. The set screw can be tightened against the valve stem to achieve a selected rotational orientation. An example of such a handle is shown in U.S. Pat. No. 4,876,766. Handles of this type can slip rotationally relative to the valve stem. Such slippage would have a minor aesthetic impact in a typical household environment, but would create no significant problem in the functioning of the household valve. However, misalignment of a handle in an industrial valve for a high purity gas flow can have a major impact on an industrial process. Hence, a handle as shown in U.S. Pat. No. 4,876,766 is not acceptable for high purity gas flows.